Automatic telephone system



R. G. RICHARDSON.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 14.1916.

Patented June 29, 192-0.

2 SHEETS-SHEET l.

R. G. RICHARDSON.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED'JULY 14.1916.

1,344,823. Patented June 29, 1920.

2 SHEETS-SHEET 2 UNITED STATES PATENT OFFICE.

v RODNEY G. RICHARDSON, OF CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, ACORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed July 14,

To all whom it may concern:

Be it known that I, RODNEY G. RICHARD- soN, a citizen of the United States of America, and av resident of Chicago, county of My invention relates to automatic telephone systems and more particularly to those automatic systems commonly known as, two-wire, systems, in which the automatic switches are controlled by impulses delivered over the two sides of the'line in series- .In systems of the above character it has been the common practice heretofore to control the release and, switching, of an automatic selector or connector switch by means of two slow-acting relays. responsive, respectively, to a long interruption of the line circuit, and a time interval following a series of short interruptions. While such systems are very satisfactory in operation and have gone into wide use it is, nevertheless, true that the slow-acting relays are a source 'of trouble, for they require careful and frequent adjustment to insure the correct performanceof their functions.

Numerous efforts have been made in the past to devise a two-wire system operating without slow-acting relays with a view to more certainty of action and reliability of adjustment, but, to the best of my present knowledge, such systems as have, been produced up to the present time either are excessively complicated or do not entirely accomplish the desired results.

My invention has for its object the provision of a simple and efficient method of two-wire control for automatic switches bv which the proper operation of the switches Specification of Letters Patent. Patented J line 29, 1920.

1916. Serial No. 109,317.

thereof will be fully described hereinafter, reference being had to the accompanying drawings, in which Figures 1 and 2, when taken in order with the lines at the ends thereof in alinement, represent diagrammatically acomplete circuit connection between a calling substation A and a called substation A in a system embodying the condenser 6. Being an automatic substation it is provided also with a pair of impulse springsTand'S controlled by the impulse wheel 9 through the medium of a finger hole dial (not shown).

To the line conductors 11 and 12 there is allotted at the exchange the individual line switch C, which may be of the general'type of line switch disclosed in British patent to R. W. James, No. 26301 of 1906; being, however, of the particular type disclosed in U. S. Letters Patent No. 1,078,690, granted Jan. 17, 1912, toFrank Newforth. Since line switches of'the above type are well known and form no part of my invention, an extended description will not be given. It will suflice to. say that through the medium of line switch C the line of substation A, when-calling is given access to a plurality of selector switches, one of which is indicated by reference character E. The conductors 21, 22, and 23 extend to multiple contacts in the banks of connectors having access to the group of lines of which the line of substation A is one, and are in use when-substation A is'being called.

For the purpose of controlling the line switch C and other line switches in the same group there is provided a master switch D which is of the general type of master switch described in British patent to R. W. James, No. 26301 of 1906; being, however, more nearly of the particular type'disclosed in British patent to T. G. Martin, No. 1419 of 1910. The function of the master switch,

as is well known, is to maintain all the idle line switches of its associated group in 0p-' erative relation with an idle trunk line.

The selector switch. E is of the general type of selector switch disclosed in U. S. Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson, and Erickson, the circuits being modified, however, in accordance with my invention in order to enable the selector switch to operate in a system in which the impulses are delivered over the two sides of the line in series.

A selector switch of the foregoing general description is operable in response to the first digit of a called number to select one of a number of groups into which the subscribers lines terminating in the exchange are divided. For this purpose the selector E may be given access to a number of groups of trunk lines, the trunk lines of each group being extended to a group of connector switches.

()ne of these trunk lines may be seen extending from bank contacts 163 164:, and 165 to the connector F which is of the general type of connector switch disclosed in U. S. Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson, and Erickson, being modified, however, according to the genei 'al plan followed in the design of the. connector switches. The connector F, as will be understood from the foregoing,- has access to a single group of subscribers lines and may be operated .in response to the last two digits of a called number to complete connection to a wanted line in the group.

The substation A and the individual line switch C are similar respectively, to the substation A and the line switch 0, which have already been briefly described.

For the purpose of supplying current for operating and talking purposes I have shown a battery B having the positive pole grounded. At It 1 have shown a ringing current generator, and at I, an interrupter for intermittently operating the ringing relay. The reference character Q indicates a busy signaling machine.

aving given a general description of the apparatus I will now proceed to a more detailed explanation of the operation of the same. Inasmuch as the operation of automatic switches of the generaltype shown herein is well known, having been fully described in the publications previously referred to, all those operations not modified by my invention will be touched upon but briefly.

Referring now to Fig. 1, the subscriber at substation A, upon removing his. receiver to initiate the call, completes an energizing circuit for the line relay 14 of the switch C over the following path: ground at G contact springs 24 and 25, line conductor -19 and the cut-off armature 20 the former,

by means of its plunger, forcing the springs 26-29, inclusive, into engagement,-respectively with contacts 30-33, inclusive, and the latter disconnecting theline conductors 11 and 12 from ground and battery, respectively, by separating contact springs 24 and 25. and 22 and 23.

By the engagement of the contact springs 26 and 29 with contacts 30 and 33, respectively, the line conductors 11 and 12 are extended to the double wound line relay 100 of the selector E, the said relay being energized over the following path: ground at G winding 102 of relay 100, contact springs 116 and 14:7, contact 33, spring 29,line conductor 11, to and through substation A, line conductor 12, sprin 26, contact 30, contact springs 150 and 149, and winding 101 of relay 100 to battery B. Upon attracting its armature, line relay 100 completes the following holding circuit for line switch (7: ground at G*, contact springs 120 121, and 122, contact springs 1 11 and 1 12, conductor 170, contact 31, spring 27, and hold ing winding 17 of line switch C to battery B. Although the circuit through the line relay 1A has already been. broken, it retains its armature long enough for the above 'described holding circuit to be established and to take effect. A branch of the holding circuit extends from spring 27 over wire 21 to multiple test contacts in the banks of the connectors having access to the line of substation A, where by a ground potential on these test contacts, the said line is made busy. The engagement of spring 28 with contaet'32 in the line switch bank operates the master switch D to advance the plungers of all the other idle line switches into position before the next idle trunk line.

Returning now to the selector E, when the line relay 100 attracts its armature a circuitfor relay 107 was closed as follows: ground at G contact springs and 121, and winding of relay 107 to battery 13. Relay 107, upon energizing, prepares a cir- 120 cuit for relay 106 which will be described. A further result of the energization of line relay 100 is the closure of a circuit including condenser 117 over the following path: ground at G condenser 117, contact springs 125 and 123, and relay 105 to battery B. The condenser 117 is charged to the potential of battery B over the above circuit and the resulting current flow serves to momentarily energize relay 105. Upon the deenergization of relay 105, a circuit for relay 106 is closed as follows; ground at G contact springs 126 and 127, contact springs 131 and 180, contact springs 134 and 135, and winding 133 of relay 106 to battery 13. Relay 106, upon attracting its armature, opens a pair of contacts in the circuit of the release magnet 103, and closes, a circuit through its own winding 132 as follows: ground at G", winding 132 of relay 106, and contact springs 137 and 138 to conductor 170. Since conductor 170 is already connected to ground at Gr over a path previously traced, no current will flow in the winding 132. It is evident, however, that if the circuit to ground G is broken relay 106 will remain locked up by its winding 132. It should be mentioned here that winding 132 is of low resistance so that whenever ground is being supplied to the holding circuit from G the conductor 21 will be maintained sufiiciently close to ground potential to guard the line of sub-' station A against intrusion.

The foregoing operations have all occurred in response to the removal of the-receiver from the hook. The calling subscriber at substation A may now 0 erate his dial in accordance with the first dlgit of the desired number, thereby breaking the continuity of his loop a number of times and resulting in a corresponding number of alternate deenergizations and energizations of line relay 100. It will be clear that when relay 100 denergizes the first time the condenser 117 is discharged over the following path: ground at G, condenser 117, contact springs 125 and 124, and winding of relay 104 to ground at G". Since the condenser 117 is immediately recharged through relay 105 at the next succeeding energizationof the line relay 100, it follows that relay 104 is operated every time relay 100 deenergizes while relay 105 operates every time relay 100 energizes, or in other words, relays 105 and 104 operate alternately from the charging and discharging of condenser 117; The relays 105 and 104 are not entirely depend: ent upon: the condenser 117 for operating current, however, for at the middle of each forward and backward stroke of the armature of relay 100 these relays are connected in series over the following path: ground at G", winding of relay 104, contact springs 124, 125, and 123, and winding of relay 105 to battery B. Thus it will-be seen that at the beginning and end of one complete energization each of the relays 104 and 105 receives current in series with the other relay while the interval between is bridged by the current flow resulting from the charging or discharging of the condenser. From these considerations it will be understood that whenever one of these relays is completely denergized the other is enerhas operated to open its contact springs 126 and 127, thereby preventing the short-circuiting of winding of 132 byground G. Accordingly, relay 106 remains energized by its winding 132 which supplies ground to the conductor 170 of the holding circuit during impulses. The intermittent operation of relay 107 in response to the interruptions of its circuit by the line relay is of no particular consequence.

At each attraction of its armature, relay 104 sends an impulse to thevertical magnet 113 over the following path: ground at G, contact springs 144 and 145, contact springs 128 and 129, winding 111 of relay 110, and winding of vertical magnet 113 to battery B. In response to these impulses the vertical magnet operates to raise the switch shaft until the wipers 160, 161, and 162 stand opposite the horizontal level of bank contacts which correspond to the digit called. Relay 110-is energized in series with the vertical magnet and, as off-normal contact 115 closes with the first upward movement of the shaft, locks itself over the following path: ground on conductor 170, contact springs 142 and 143, interrupter contact 172, off-normal contact 115, and Winding 112 to battery B. By closing its contact springs 155 and 156 relay 110 prepares a circuit for the rotary magnet 114 and, by separating its contact springs 141 and 142, prevents the line relay 100 fromshort-circuiting the Winding 132 of relay 106 at its next energization.

It should be noted at this point that both terminals of switching relay 109 are now connected to conductor 170 and to ground, the'left hand terminal being connected direct, while the right hand terminal is connected by way of interrupter contacts'171 and 172, and'the contact springs 143 and 142. It'will be noted, furthermore, that the right hand terminal of relay 109 extends to battery 13 by way of interrupter contact 171, oif-normal contact 115, and winding 112 of relay 110; but since the relay 109 is shortcircuited, as previously described, it, of course, remains inoperative.

Immediately after the last decnergization of line relay 100 the relays 104 and 105 cease operating, whereupon the previously mentioned rotary magnet circuit is completed as follows: ground at G contact springs 126 and 127, contact springs 131 and 130, contact springs 134 and 135, contact springs 155 and 156, and winding'of rotary magnet 114 to battery B. Upon attracting its armature the rotary magnet operates to rotate the switch shaft until the wipers 160, 161, and 162 engage the first set of bank contacts in the level to which they have been raised. Near the end of its stroke the armature of the rotary magnet opens the interrupter contacts 171 and 172, the opening of these contacts resulting in the denergization of relay 110. Upon de'e'nergizing, relay 110 breaks the circuit of the rotary magnet which magnet, upon deenergizing in turn, again closes the interrupter contacts 171 and 172. The

operation now depends upon whether the private bank contact with which wiper 161 is in engagement is grounded or not. If the first trunk line is busy the private bank contact will be grounded and the following circuit will be effective: ground on private bank contact, private wiper 161, contact springs 153 and 152, interrupter contact 171, off-normal contact 115, and winding .112 of relay 110 to battery B. By means of the above circuit the relay 109 is short'circuited (its right hand terminal being connected to the circuit at interrupter contact 171) and the relay 110 is again energized, therebly again closing the rotary magnet circuit. t follows then that as long as the wiper 161 engages busy or grounded private bank contacts the rotary magnet will be operated intermittently, relay 110 operating as an impulse sender, to rotate the wipers from contact set to contact set in search of an idle trunk line. Assuming that the contact set 163-165 is idle and theprivate bank contact 164 is free of ground, when the wiper 161 engages contact 164 and the interrupter contact 171 closes upon the last retraction of the rotary armature, the relay 109 will not be tact springs 144 and 145; connects the pri-' vate wiper 161 to conductor 170 by closing contact springs 153 and 154, and through the medium of contact springs 146 to 151, inclusive, disconnects the extended line conductors 11 and 12 from the line relay 100 and further extends them by way of wipers 160 and 162 and bank contacts 163 and 165 to the 231 and 230, andlwinding 207 of relay 206 to battery 13. Upon energizing, relay 206 closes a locking circuit for itself from ground G" by way of off-normal springs 222 and 223, contact springs 241 and 242, and winding 208 to battery B; and in addition closes the following holding circuit: ground at G, contact springs 244 and 243, bank contact 164, wiper 161, and contact springs 153 and 154 to wire-junction 173, where the circuit divides, one branch extending by way of a previously traced circuit through relay 109 to battery B, and the other'branch joiningconductor 170 at wire-junction 174 to supply ground to the previously traced holding circuit for line switch C.

It will be observed that since conductor 170 is now connected direct to ground as just described, the winding of relay 106 will be short-circuited and since the circuit of its other winding 133 is now open, relay 107 having deenergized, the said relay 106 will retract its armature, thereby opening its locking circuit at contact springs 137 and 138 and preparing a circuit for the release magnet 103 at contact springs 139 and 140. It is understood, of course, that the holding circuit described in the preceding paragraph is completed before winding 132 is shortcircuited by ground Gr which is the normal condition with the line relay 100 and relay 107 deenergized. The delay in closing the latter circuit is caused by the final discharge of condenser 117 through relay 104 in a manner readily perceived.

The calling subscriber may now operate his calling device in accordance with the second digit of the desired number, resulting now in a corresponding number of deenergizations of the line relay 200 of the connector F. As the line relay200 vibrates its armature the relays 204 and 205 operate precisely as described in the case of relays 104 and 105 of the selector E, except that in the resent case a circuit is maintained closed instead of being held open as will be made clear hereafter.

Each time relay 204 attracts its armature, an impulse is sent to the vertical magnet 215 over the following path: ground at G, contact springs 237 and 238, vertical magnet 215, and side switch wiper 220 (in first position) to battery B. In response to these impulses the vertical magnet operates to raise the switch shaft step by step until the wipers 270, 271, and 272 stand opposite the horizontal level of bank contacts in which are located the line terminals of substation maintaining this relay energized has already been closed, however, and may be traced as follows: ground at G, winding of private control relay 209, contact springs 235 and 236 or contact springs 239 and 240,

contact springs 241 and 242, and winding 208 of relay 206 to battery B. The private control relay 209 is also energized over the foregoing circuit and closes'an energized circuit for the private magnet 211 in the well known manner. When relay 205 de-- energizes after the last impulse of the series the above described circuit including the private control relay is broken, relay 206 remaining energized, however, by the circuit through its winding 207 now closed by the line relay 200. Upon the deenergiza- .tion of theprivate control relay and the consequent interruption of the circuit of the private'magnet 211, the side switch wipers are advanced to their second position in the usual manner. As side switch wiper 221 engages its second position contact point a new locking circuit is completed for relay 206 as follows: ground at G, side switch wiper 221, rotaryoff-normal springs 269, contact springs 241 and 242, and wind.- ing 208 of relay 206 to battery B.

The calling subscriber may now manipulate his dial' in accordance with the final digit of the called number, resulting as before in a series of de'energizations of the line relay 200 and the alternate operation of relays 204 and 205. Side switch wiper 220 being in its second position, relay 204 transmits an impulse at each attraction of its armature to the rotary magnet 216 over the following path: ground at G, contact springs 237 and 238, contact springs 251 and 252, rotary magnet 216, and side switch wiper 220 to battery B. In response to these impu ses the rotary magnet operates to rotate th wipers 270, 271, and 272 until they arrive, respectively, at bank contacts 273,274, and 275 which contacts com rise the terminal of the line of substation in the bank of connector F. At the first rotar movement of the switch shaft the rotary o normal springs 269 are separated, therebybreaking the locking circuit from ground G 'l. As before, however, a new circuit including the private control relay 209 has already been completed by the relays 204 and 205, whereby the relay 206 is retained in operated position and the private control relay 209 is energized to again close the circuit of the private magnet 211. When relay 205 deenergizes after the last impulse of the series the circuit including the private control relay 209 and winding 208 of relay 206 is broken, the latter relay remaining operated by its winding 207 as before.

The private control'relay 209, however, is deenergized and in turn breaks the circuit of the private magnet which latter controls the side switch wipers to advance them to their third position in the well known manner. (it being assumed that the line of substation A was idle when called).

As side switch wiper 219 comes into engagement with its third position contact point the following circuit is closed 'for the cut-off or hol'din winding 280 of line switch C ground at 5 bank contact 274, and holding winding 280 to battery B. As a result of the closure of this circuit the 'cutoil armature 281 is attracted, thereby disconnecting the line of substation A from its connections in line switch C. A branch of the foregoing circuit extends to multiple private or test contacts similar to contact 274 in the banks of the remaining connectors having access to the line of substation A where by a ground potential on these test contacts the said line is made busy.

By the engagement of side switch wipers 217 and 218 with their third position contact points the connection is completed to the called line. At the same time, by the advance of side switch wiper 220 to its third position, a circuit is completed for the ringing relay '214 which now be 'ns operating intermittently by reason 0 the interrupter I to project ringing current from the generator R out over the called line to signal the called subscriber.

When the called subscriber atsubstation A removes his receiver in responsetothe' ringing of his bell a circuit including the double wound back bridge relay 210 is completed in the well known manner. Relay 210, upon attracting its armature closes a circuit for the ring cut-off relay 213 which A complete talking connection has now.

been established and the calling and called subscribers may converse without further efiort. Current for the transmitter at substation A is supplied through the windings of the double wound line relay 200 while current for the transmitter at substation A is supplied through the windings of the double wound back bridge relay 210. The voice currents take the path shown in the heavy lines, which is thought to be' so obvious as to require no further explanation.

When the conversation is finished both calling and called subseriberswill replace their receivers. B the replacement of the receiver at substation A the circuit of the line relay 200 is broken. Upon deenergizing, the line relay 200 breaks the circuit including the winding 207 of relay 206. There being no closed locking circuit for its winding 208, relay 206 deenergizes immediately and separates contact springs 241 and 242 in the circuit of its winding 208. As a further result, ground at G is disconnected from the holdlng circuit and a circuit is completed for the release magnet 203 in an obvious manner. The release magnet 203, upon energizing, operates to restore the switch shaft and the side switch wipers to normal position, after which. its circuit is broken by the upper set of shaft controlled oif-normal springs. a

By the removal of ground G from the holdingcircuit, the holding winding of the line switch C is deenergized, whereby the line switch is restored to normal position by the withdrawal of its plunger 'from the bank; and the line switching relay 109 of the selector E is deenergized. As a result of the latter operation, a circuit is closed for the release magnet 103 of the selector as follows: ground at G", contact springs 144 and 145, contact springs 139 and 140, windingof release magnet 103, and off-normal springs 116 to battery B. The release magnet 103, upon energizing, operates to restore the shaft of the selector switch to normal position in the usual manner, after which its circuit is broken at the off-normal springs 116.

Inasmuch as the operation of a connector switch of the general type shown herein when connection is attempted with a busy line is well known and is not modified in any respect by my invention, such operation will be described in a very brief manner. It is understood that when the line of substation A is busy the multiple 'test contact 274 will be connected to ground. Now when the private control relay 209 deenergizes after the last series of'impulses a circuit is completed from ground on the test contact ofthe bus line by way of the'wiper 271, the side switc wiper 219 (in second position), contact springs and winding of the test relay 212, contact springs of the private control relay 209, and winding of the private magnet 211 to battery B. The private magnet is maintained energized by the closure of the foregoing circuit and holds the side switch wipers in second position to prevent connection with the called line. The test relay 212, upon energizing, locks itself and the private magnet toground at G" and applies a busy tone .to the calling line by way of side switch wiper 218. The, calling subscriber, being thus informed that the called line is temporarily inaccessible, will re'place his receiver, there y restoring the automatic switches to normal position in the manner hereinbefore described.

It will beseen from the foregoing that I have devised an exceedingly efiicient and reliable two-wire automatic telephone-system in which the automatic switches are controlled exclusively through the medium of ordinary fast or quick acting relays, the usual slowacting or sluggish relays having been entirely eliminated.

While I' have found it convenient in explaining my invention to show and describe a certain specific embodiment thereof, I do not wish to limit no self to the exact disclosure shown, for that modifications will be made in the future either to adapt the invention to other types of apparatus or to keep pace with otherinventions tending to simplify the apparatus. I desire, therefore,-to include and have protected by Letters. Patent all forms and modifications of my invention which may come within the scope of the appended claims.

What I "claim as my invention is:

1. In a telephone system, the combination with an automatic switch provided with operating and restoring magnets, of a closed controlling circuit for said switch, means for causing interruptions of said circuit, a plurality of quick acting relays responsive to said interruptions, and circuits for said magnets controlled by said relays.

2. In a telephone system, the combination with a metallic line circuit extending to a central exchange and means for transmittingcurrent impulses over the two sides thereof in series, of a progressively movable switching mechanism provided with a plurality of motor magnets, and a plurality of quick acting relays in said switch responsive to said current impulses for controllingsaidmagnets.

3. In a telephone system, the combination with a metallic line circuit extending to a central exchange and means for transmitting current. impulses over the two sides thereof in series, of a progressively movable switching mechanism provided with a plurality of motor magnets, and a plurality of relays in said switch for controlling said magnets, each of said relays responsive to each of said impulses.

4'. In a telephone system, the combination with a metallic line circuit extending to a central exchange and means for transmitting current impulses over the two sides thereof in series, of a progressively movable switching mechanism providedwith a plurality of motor magnets, and a plurality of relays in said switch-having sole control of said magnets, said relays having uniform time constants.

5. In a telephone system, the combination with a metallic line circuit and means for transmitting current impulses over the two sides thereof in series, of an automatic selector switch having primary and secondary selecting functions, primary and secondary motor magnets forfoperating said switch to perform said functions, and a plurality of relays for controlling said magnets, said 'relays each responsive to each of said impulses.

6. In a telephone system, the combination with a metallic, line circuit and means for transmitting current impulses over the two sidesthereof in series, of an automatic selector switch having primary and secondary selecting functions, primary andsecondary motor magnets for operating sa'id switch to perform said functions, separate circuits for said magnets, a relay responsive to said impulses for controlling the circuit of said primary magnet, and a second relay responsive to said impulses for controlling in con-. junction with said first relay the circuit of said secondary magnet.

.7. In a telephone system, the combination with a metallic line circuit and means for transmitting current impulses over the two sides thereof in series, of a progressively movable switching mechanism provided witha pair of motor magnets, a plurality of relays each responsive to all of said impulses, a circuit for one of said magnets controlled by one of said relays, and a circuit for the other of said magnets controlled conjointly by all of said relays.

8. In a telephone system, the combination with a metallic line circuit and means for transmitting current impulses over the two sides thereof in series, of a progressively movable switching mechanism provided with a pair of motor magnets, a circuit for one of said magnets, and a pair of relays operated alternately in response to said impulses for controlling said circuit.

9. In a telephone system, the combination with a metallic line circuit and means for transmitting current impulses over the two sides thereof in series, of a progressively movable switching mechanism provided with a pair'of motor magnets, means for controlling one of said magnets in response to said impulses to effect aprimary movement of said switch, a circuit for the other magnet prepared at the first impulse, a pair of relays responsive alternately to said impulses, and'means controlled by said relays to maintain said circuit open until said primary movement is completed.

short or long interruptions in said circuit,

a line relay for said switch in said circuit responsive to said interruptions, and a plurality of relays responsive to each operation of said line relay for controlling said magnets. I v

12. In a telephone system, the combination with an automatic switch having operating and restoring magnets, of a controlling circuit for said switch, means for causing short or long interruptions in said circuit, a line relay for said switch in said circuit and responsive to said interruptions, a re lease relay for controlling said restoring magnet, anda plurality of relays responsive to each operation of said line relay for controlling said operating magnet and said release relay.

13.In a telephone system, the combination with an automatic switch having operating and restoring magnets, of a controlling circuit for said switch, means for causing short or long interruptions in said circuit,

a line relay for-said switch in said circuit and responsive to said interruptions by retracting-its armature, and a pair of relays for controlling said magnets, said relays operated alternately upon successive attractions and retractions of said line relay armature.

14. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of current impulses. in said circuit, operating means in said switch responsive to said impulses, means for restoring'said switch to normal position, a relay initially energized upon the first closure of said controlling circuit pulses in said circuit, operating means in.

said switch responsive to said impulses, a restoring magnet for said switch, a circuit for said magnetclosed, at one point upon the first movement of said switch, a relay for maintaining said magnet circuit open at another point, a circuit for said relay, and means for maintaining a continuous flow of current in said relay circuit during a series of impulses.

16. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of-current impulses in said circuit, operating means in said switch responsive to said impulses, a restoring magnet for said switch, a circuit for said magnet closed at one point upon the first movement of said switch, a relay for circuit, and means responsive thereto for.

stopping the flow of current in said relay circuit to permit the restoration of said switch.

17. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of current impulses in said circuit, operating means in said switch responsive to said impulses, means for restoring said switch to normal position, a relay initially energized upon the first closure of said controlling circuit for preventing the operation of said restoring means, an auxiliary circuit for said relay, means for maintaining acontinuous flow of current in said auxiliary circuit during a series of impulses, said means comprising a pair of relays, and a line relay responsive to said impulses for operating the relays of said pair. alternately.

18. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of current impulses in said circuit, operating means in said switch responsive to said impulses, a restoring magnet for said switch, a circuit for said magnet closed at one point upon the first movement of said switch, a relay for maintaining said magnet circuit open at another point, a circuit for said relay, means for maintaining a continuous flow of current in said relay circuit during aseries of impulses, said means comprising a pair of relays, and a line relay responsive to said impulses for operating the relays of said pair alternately.

19. in a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of current im-, pulses in said circuit, operating means in said switch responsive to said impulses, means for restoring said switch to normal position, a relay initially energized upon the first closure of said controlling circuit for preventing the operation of said restoring means, an auxiliary circuit for said relay, means for maintaining a continuous flow of current in. said auxiliary circuit dur ing a series of impulses, said means comprising a pair of relays and a condenser, together with means responsive to said impulses for charging and discharging said condenser through said relays.

20. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of current impulses in said circuit, operating. means in said switch responsive to said impulses, a restoring magnet for said switch, circuit for said magnet closed at one point upon the first movement of said switch, a relay for maintaining said magnet circuit open at another point, a circuit for said relay, means for maintaining a continuous flow of current in said relay circuit during a series of impulses, said means comprising a pair of relays and a condenser, together with means responsive to said impulses for charging and discharging said condenser through said relays.

21. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing a series of current impulses in said circuit, operating means in said switch responsive to said impulses, means for restoring said switch to normal position, a relay initially energized upon the first closure of said controlling circuit for preventing the operation of said restoring means, a locking circuit for said relay, means for opening said locking circuit upon the first movement of said switch, and means for closing said locking circuit over a different path during a series of impulses.

22. In a telephone system, a line terminatingin an automatic switch, means for trans mitting a series of impulses over said line, operating means in said switch responsive to said impulses, a local control circuit for said operating means, and means for holding said circuit closed during a series of impulses, said means comprising a pair of quick acting relays and means for energizing them.

23. In a telephone system, a line terminating in. an automatic switch, means fortransmitting a series of impulses over said line, operating means in said switch responsive to said impulses, a local control circuit forsaid operating means, and means for holding said circuit closed during a series of impulses, said means comprising a pair of relays and means responsive to said series of impulses for operating the relayp of said pair alternately.

24ln a telephone system, an automatic switch and a controlling circuit therefor, means for producing series of current impulsesin said circuit, operating magnets in said switch, switching means for controlling the circuits of said magnets, a relay for controlling said switching means, a circuit for said relay, and means for maintaining a continuous flow of current in said relay circuit during a series of impulses.

25. In a telephone system, an automatic switch and a controlling circuit therefor, means for producing series of current impulses in said circuit, operating magnets in said switch, switching means for controlling the circuits of said magnets, a relay for controlling said switching means, a circuit for said relay, and means for maintaining a continuous flow of current in said relay circuit during a series of impulses, said means comprising a pair of relays, togetherwith means responsive to said impulses for operating said relays alternately.

26. In a telephone system, an automatic switch anda controllingcircuit therefor, means for producing'series of current impulses in said circuit, operating magnets in said switch, switching means for controlling the circuits of said magnets, a relay for controlling said switching means,a circuit for said relay, and means for maintaining a continuous fiow of current in said relay circuit during a series of impulses, said means comprising a pair of relays, a condenser, and a line relay responsive to said impulses for charging said condenser in series with one relay of said pair and discharging it in series with the other.

27. In a telephone system, the combination with an automatic switch and a controlling circuit therefor, of means for producing current impulses in said circuit, operating magnets in said switch responsive to said impulses, switching means for controlling the circuits of said operating magnets, and a pair of relays responsive to said impulses for controlling said switchin means.

28. In a telephone system, the combination with an automatic switch and a'controlling circuit therefor, of means for producing current impulses in said circuit, operating magnets in said switch responsive to said impulses, switching means for controlling the circuits of said operating magnets. a pair of relays for conjointlycontrolling said switching means, and means whereby the relays of said pair are caused to alternately vibrate their armatures in response to said impulses.

29. In a telephone system, the combination with an automatic switch and a controlling circuit therefor, of means for ,pro-' ducing current impulses in said circuit", operating magnets in said switch responsive to said impulses, switching means for controlling the circuits of said operating magnets, a pair of relays for conjointly controlling said switching means, and means whereby the relays of said pair are caused to alternately vibrate their armatures in response to said impulses, said last means" comprising a line relay in said controlling circuit, a condenser, and charging and discharging circuits for said condenser including the relays of said pair.

30. In a telephone system, the combination with an automatic switch and a line relay therefor, of a control circuit for said line relay, means for producing intermittent current impulses in said circuit to cause alternate energizations and deenergizations of said relay, operating magnets for said switch, a second relay operated momentarily at each de'einergization of said line relay to control a first one of said magnets, switching means to shift the control of said second relay to another of said magnets, and

a third relay operated momentarily at each energization of said line relay and adapted conjointly with said second relay to control said switching means.

31. Ina telephone system, the combination with an automatic switch and a line relay therefor, of a control circuit for said line relay, means for producing intermittent current impulses in said circuit to cause switch provided with a plurality of oper ating magnets, a controlling circuit for said switch and means for producing uniform series of current impulses therein, a relay responsive to all impulses of a series to control a first one of said magnets, an auxiliary switch for shifting the control of said relay to another of said magnets, and a second relay responsive to all impulses of a series and operating conjointly with said first relay to control said auxiliary switch. 33. In -a telephone system, an automatic progressively movable switch having a plurality of operating magnets, a controlling circuit for said switch, means for producing series of current impulses in said circuit, a relay responsive to each impulse of a series for controlling one of said magnets, switching means for shifting the control of said magnets, and a second relay responsive to each impulse of a series and operating conjointly with said first relay to control said switching means.

34=.'In a telephone system, the combination with an automatic switch and an operating magnet therefor, of a circuit for said operating magnet, a relay for controlling tion with an automatic switch and a motor magnet therefor, of a line relay, a closed circuit for said relay and means for interrupt: ing the same, a circuit for said magnet, a relay for controlling said magnet circuit, a condenser, and means controlled by said line relay for alternately charging said condenser and discharging the same through said controlling relay, whereby said motor magnet may be operated in accordance with interruptions of the circuit of said line relay.

'37. In a telephone system, an automatic switch, a motor magnet for said switch, a relay in said switch and a circuit therefor, means for closing-said circuit and for interrupting the same thereafter to operate and deenergize said relay, a condenser, a circuit for charging said condenser closed when the said relay is operated, a second relay for controlling said motor magnet, and a circuit for discharging said condenser through said second relay closed when said first relay is deenergized.

38. In a telephone system, the combination with an automatic switch and a motor magnet therefor, of a line relay in said switch, a closed circuit for said relay and means for interrupting the same, a circuit for said magnet and a controlling relay therefor, a condenser, means for charging said condenser when the line relay is operated, and means for discharging said condenser through said controlling rela when said line relay is deenergized, where y said motor magnet may be operated in accordance with interruptions of the circuit of said line re ay.

39. In a telephone system, an automatic switch, a local control circuit in said switch, controllin relays for said circuit and means whereby 'uring the operation of said switch said relayscoiiperate to maintain said circuit continuously open independent of the continuous energization or deenergization of any one of them.

40. In a telephone system, an automatic switch, a local control circuit in said switch, controlling relays for said circuit and means whereby during the operation of said switch said relays cooperate to maintain said circuit continuously closed independent of the continuous energization or denergization of any one of them.

41. An automatic switch control system comprising relays, means for operating said relays alternately, the time intervals during which said relays are operated overlapping, and a switch control circuit maintained open by the conjoint action of said relays while they are being operated.

42. An automatic switch control system comprising relays, means for operating said relays alternately, the time intervals during which said relays are operated overlapping, and a switch control circuit maintained closed by the conjoint action of said relays while they are being operated.-

43. An automatic switch control system comprising a plurality of normally inactive tion with an automatic switch and means for operating the same, of a release magnet, a locking relay for controlling said magnet, means for energizing said relay at the beginning of the operation of ,said switch, and means for short circuiting the locking winding of said relay to deenergize the same to cause the release of the switch.

45. In a telephone system, an automatic switch having primary and secondary movement, a controlling circuit and means for delivering current impulses thereover to control the operation of said switch, mechanism in said switch controlling the changeover from primary to secondary movement, and relays responsive to said impulses for controlling said mechanism, each of said relays operating its armature with each impulse.

46. In a telephone system, an automatic switch having primary and secondary motion, a controlling circuit for said switch and means for producing current impulses therein, a relay for said switch in said circuit responsive to said impulses, another relay for said switch controlled by said first relay, a circuit for said second relay, and means controlled by said first relay for producing an induced current impulse for operating said second relay, mechanism in said switch for changing over from primary to secondary movement said mechanism controlled by said second relay.

47. In a telephone system, an automatic switch having primary and secondary operating magnets, means for primarily operating said switch through the medium of said primary magnet, a c1rcuit for said second- 110 ary magnet, means for closing said circuit at one point at the beginning of the primary operation, and relays operating alternately to hold said circuit open at another point until the primary operation is completed.

48. In a telephone system, an automatic switch including a line relay for controlling the operation thereof and a release relay for preventing the release of said switch while the same is in use, a circuit for said release relay closed by said line relay when the switch is in use but not being operated, a second circuit for said release relay, and means for closing said second circuit while the said switch is being operated.

49. In a telephone system, an automatic switch provided with a motor magnet, a control circuit for said switch, a relay and a condenser, a second relay in said control circuit for alternately charging said condenser and discharging the same through said first relay, and a circuit for said motor magnet controHed by said first relay.

50. In a telephone system, an automatic switch provided with primary and secondary operating magnets, a control circuit for said switch, a relay and a condenser, a second relay in said control circuit for alternately charging said condenser and discharging the same through said first relay, and circuits for said magnets controlled by said first relay.

51. In a telephone system, an automatic switch provided-with a motor magnet and a line relay, a control circuit extending to said switch and terminating in said line relay, means for producing current changes in said circuit, the said relay being responsive to such changes to control said magnet in accordance therewith, and means intervening between the said relay and magnet causing'the latter to respond to said current changes uniformly regardl ss of irregularities therein.

52. In a telephone system, an automatic switch provided with a motor magnet and a line relay, a control circuit extending to said switch and terminating in said line relay, ineans for producinga plurality of long, short, or irregular current changes in said circuit, the said relay being responsive to such changes to bring about the operation of said magnet, and standardizing means intervening between said relay and magnet causing the latter to respond to said current changes uniformly without regard to their length or to the irregular character thereof.

Signed by me at Chicago, Cook county, Stateof Illinois, this 29th day of June, 1916.

RODNEY G. RICHARDSON. 

